Scanning Probe Microscopy (SPM) laboratories have been manipulating individual atoms and molecules for decades. Iancu, V. and S. W. Hla, Realization of a four-step molecular switch in scanning tunneling microscope manipulation of single chlorophyll-a molecules. Proc Natl Acad Sci USA, 2006. 103(37): p. 13718-21; Duwez, A., et al., Mechanochemistry: targeted delivery of single molecules. Nature Nanotechnology, 2006. 1(2): p. 122-125; Stroscio, J. and R. Celotta, Controlling the Dynamics of a Single Atom in Lateral Atom Manipulation. Science, 2004. 306: p. 242-247; Morita, S., et al., Atom-selective imaging and mechanical atom manipulation using the non-contact atomic force microscope. J. Electron Microsc., 2004. 53(2): p. 163-168; Oyabu, N., et al., Mechanical vertical manipulation of selected single atoms by soft nanoindentation using near contact atomic force microscopy. Phys. Rev. Lett., 2003. 90(17); Lauhon, L. and W. HO, Control and Characterization of a Multistep Unimolecular Reaction. Physical Review Letters, 2000. 84(7): p. 1527-1530; Hla, S. W., et al., Inducing All Steps of a Chemical Reaction with the Scanning Tunneling Microscope Tip—Towards Single Molecule Engineering. Physical Review Letters, 2000. 85(13): p. 2777-2780; HO, W. and H. LEE, Single bond formation and characterization with a scanning tunneling microscope. Science 1999(286): p. 1719-1722; Bartels, L., G. Meyer, and K. Rieder, Dynamics of Electron-Induced Manipulation of Individual CO Molecules on Cu(111). Physical Review Letters, 1998. 80(9); Huang, D. H. and Y. Yamamoto, Physical mechanism of hydrogen deposition from a scanning tunneling microscopy tip. Appl. Phys. A, 1997. 64: p. R419-R422; Bartels, L., G. Meyer, and K. H. Rieder, Controlled vertical manipulation of single CO molecules with the scanning tunneling microscope: A route to chemical contrast. Applied Physics Letters, 1997. 71(2): p. 213; Bartels, L., G. Meyer, and K. Rieder, Basic Steps of Lateral Manipulation of Single Atoms and Diatomic Clusters with a Scanning Tunneling Microscope Tip. Physical Review Letters, 1997. 79(4): p. 697-700; Meyer, G., B. Neu, and K. Rieder, Controlled lateral manipulation of single molecules with the scanning tunneling microscope. Applied Physics A, 1995. 60: p. 343-345; MEYER, G., B. NEU, and K. RIEDER, Building Nanostructures by Controlled Manipulation of Single Atoms and Molecules with the Scanning Tunneling Microscope. phys Stat Sol (b), 1995. 192: p. 313-324; Stroscio, J. and D. Eigler, Atomic and Molecular Manipulation with the Scanning Tunneling Microscope. Science, 1991. 254: p. 1319-1326; Eigler, D., C. Lutz, and W. Rudge, An atomic switch realized with the scanning tunneling microscope. Nature, 1991. 352: p. 600-603; Eigler, D. M. and E. K. Schweizer, Positioning Single Atoms with a Scanning Tunnelling Microscope. Nature, 1990. 344: p. 524-526; Hersam, M. C., N. P. Guisinger, and J. W. Lyding, Silicon-based molecular nanotechnology. Nanotechnology, 2000. 11(2): p. 70; Wang, Q. H. and M. C. Hersam, Nanofabrication of heteromolecular organic nanostructures on epitaxial graphene via room temperature feedback-controlled lithography. Nano Lett, 2011. 11(2): p. 589-93; Owen, J. H. G., et al., Patterned atomic layer epitaxy of Si/Si(001):H. Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2011. 29(6): p. 06F201; Randall, J., et al., Atomic precision lithography on Si. J. Vac. Sci. Technol. B, 2009; Ruess, F. J., et al., Realization of atomically controlled dopant devices in silicon. Small, 2007. 3(4): p. 563-7; Ruess, F., et al., Toward Atomic-Scale Device Fabrication in Silicon Using Scanning Probe Microscopy. Nano Letters, 2004. 4(10); Basu, R., et al., Room temperature nanofabrication of atomically registered heteromolecular organosilicon nanostructures using multistep feedback controlled lithography. Applied Physics Letters, 2004. 85(13): p. 2619; Hersam, M., N. Guisinger, and J. Lyding, Silicon-based molecular nanotechnology. Nanotechnology, 2000; Sugimoto, Y., et al., Complex Patterning by Vertical Interchange Atom Manipulation Using Atomic Force Microscopy. Science, 2008. 322: p. 413-417; Kawai, S., et al., Atom manipulation on an insulating surface at room temperature. Nat Commun, 2014. 5: p. 4403. These efforts have generally been limited to simple two-dimensional structures, but the techniques are powerful enough to have already demonstrated basic molecular-scale logic (Heinrich, A., et al., Molecule Cascades. Science, 2002. 298: p. 1381-1387) and to have inspired commercial efforts to build atomically-precise structures, including work towards quantum computers (see Randall and Ruess, supra).
While promising, this work falls short of the original vision of atomically-precise products, including molecular machines (Feynman, R., There's Plenty of Room at the Bottom. Caltech Engineering and Science, 1960. 23(5): p. 22-36.) due to the use of atom manipulation techniques that do not lend themselves to commercial manufacture.
Previously, atom manipulation was performed using one of three techniques: Feedback Controlled Lithography (FCL), horizontal atom manipulation, or vertical atom manipulation. FCL uses a scanning probe tip to remove atoms (e.g., passivating hydrogens) from a surface, creating chemically-reactive radical patterns on that surface, followed by bulk chemical reactions that take advantage of the new radical sites to create a surface modified at specific atomic locations. Horizontal atom manipulation relies upon dragging atoms across flat surfaces to place them at specific locations, in effect decorating a surface with atomically-precise designs. Vertical atom manipulation, often referred to as mechanosynthesis, includes the deposition of single atoms or molecules, such as CO, as well as vertical atom interchange, which allows a surface and tip atom to be swapped. Herman, A., Toward Mechanosynthesis of Diamondoid Structures: X. Commercial Capped CNT SPM Tip as Nowadays Available C2 Dimer Placement Tool for Tip-Based Nanofabrication. Journal of Computational and Theoretical Nanoscience, 2013. 10(9): p. 2113-2122; Herman, A., Toward Mechanosynthesis of Diamondoid Structures: IX Commercial Capped CNT Scanning Probe Microscopy Tip as Nowadays Available Tool for Silylene Molecule and Silicon Atom Transfer. Journal of Computational and Theoretical Nanoscience, 2012. 9(12): p. 2240-2244; Tarasov, D., et al., Optimal Tooltip Trajectories in a Hydrogen Abstraction Tool Recharge Reaction Sequence for Positionally Controlled Diamond Mechanosynthesis. J. Comput. Theor. Nanosci., 2010. 7(2): p. 325-353; Oyabu, N., et al. Mechanical Vertical Manipulation of Single Atoms on the Ge(111)-c(2×8) Surface by Noncontact Atomic Force Microscopy. in Seventh International Conference on non-contact Atomic Force Microscopy. 2004. Seattle, Wash. See also Morita, Oyabu, Sugimoto, and Kawai supra.
Each of these atom manipulation techniques modifies a single atomic layer on a surface and does so using a very limited palette of reactions and reactants and cannot manufacture complex, three-dimensional products.
Previous work by the current inventors, including U.S. Pat. No. 8,171,568, U.S. Pat. No. 8,276,211, U.S. Pat. No. 9,244,097, U.S. Patent Application No. 20150355228 and U.S. Patent Application No. 20160167970, sought to address some of the shortcomings of prior atom manipulation techniques via an improved version of mechanosynthesis. These references describe how to build atomically-precise tips which facilitate more diverse reactions, and how to design series of reactions, “build sequences,” that allow for the fabrication of complex, three-dimensional structures, among other improvements. However, room for additional improvement still exists.